The present invention is an outgrowth of the air pallet and air bearing patient mover development set forth in U.S. Pat. No. 3,948,344 entitled "LOW COST AIR PALLET MATERIAL HANDLING SYSTEM" issued Apr. 6, 1976, and U.S. Pat. No. 4,272,856 entitled "DISPOSABLE AIR-BEARING PATIENT MOVER AND VALVE EMPLOYED THEREIN" issued June 16, 1981, both assigned to the common assignee.
Planar air pallets of such type employ at least one flexible material bottom sheet for partially defining a plenum chamber with said one sheet being perforated, as by way of small pin holes, literally in the thousands, over a surface area defined by the imprint of the load, which pin holes face an underlying, generally fixed planar support surface, and wherein the pin holes open unrestrictedly to the interior of the plenum chamber. When the plenum chamber, formed by top and bottom thin flexible sheets, is pressurized by low pressure air, the underlying sheet is in contact over the complete extent of the pin holes with the generally planar support surface. Initially in the air pallet or air pallet type patient mover, the flexible film sheets act like a balloon, and the accumulation of air under pressure initially jacks the load above the top flexible sheet to a given height, whereby the bottom flexible sheet in following the same causes the first row or rows of perforations to lift off the underlying planar support surface, while air also passes through all of the perforations and creates a frictionless air bearing of relatively small height between the underlying support surface and the bottom of the perforated flexible sheet. An equilibrium position is reached where a given number of the perforations rise away from the rigid support structure to permit the air to escape freely from the plenum chamber to the atmosphere and jacking of the load ceases, with the air bearing maintained.
In all air pallets, including patient movers, it is necessary to provide controlled pillowing of the flexible film or films which may totally or partially define the plenum chamber and to thus establish, by jacking the load to a predetermined height, the ability of the air pallet to ride over the surface projections on the underlying support surface. At the same time, excess pressurization of the plenum chamber may cause ballooning of the thin flexible sheet or sheets to an extent where tilting occurs and the load may roll off of the top of the air pallet (or patient mover).
When the load rests on the air pallet prior to pressurization of the plenum chamber, the load tends to press the perforated flexible sheet in contact with the underlying support surface (floor). This prevents the entry of air under light pressure into the plenum chamber and subsequent escape of the air through the perforations to create the air bearing. Air dispersion means are required either interiorly or exteriorly of the plenum chamber, to insure pressurization of the plenum chamber, jacking of the load and subsequent creation of the air bearing. While the air pallet type patient mover of U.S. Pat. No. 4,272,856 has operated satisfactorily, particularly in moving a patient placed thereon and from relatively rigid underlying support surfaces such as those defined by an operating table or a wheeled transport gurney, such patient movers do not have universal application in hospitals, and particular requirements must be met for utilizing air pallet type patient movers peculiar to operating room requirements, X-ray machines, and apparatus where the patient is maintained in positions other than flat. In all such applications, it must be kept in mind that the patient's body is of irregular configuration in addition to the fact that the mass of the patient is also irregularly distributed, i.e. the central torso is much heavier than the head at one end or the legs at the opposite end of the torso. Care must be taken to insure the patient's comfort during transport, and while on the operating table, X-ray machine support, etc.
It is, therefore, a primary object of the present invention to provide an improved air bearing type patient mover which is particularly applicable for moving the patient to and from various underlying generally rigid support surfaces, particularly where those surfaces may be changed to and from a flat horizontal configuration, where the air bearing surface area is matched to the mass geography of the patient, wherein the patient mover includes means for ready hand grasping from either side to facilitate effortless movement of the patient on the patient mover supported by the air bearing defined by the perforated pattern area, and wherein air distribution to the plenum chamber, jacking of the patient, and the creation of a frictionless air film bearing beneath and bottom thin flexible sheet and at the perforated pattern area is assured.